Iris odaesanensis ex South Korea. You're right, Mark: It does bloom quite suddenly. And this is the first bloom, so I thought I was watching closely! I never even noticed the buds coming.....
Rick Rodich zone 4a. Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA
An "update" on Iris odaesanensis from May 22cd
Iris lacustris does fine in a shadier garden, despite its native habitat of open lakeshores.
Iris cristata 'Vein Mountain' seems to vary from year to year in the shading of the flower color. This year it seems to be middle of the road.
And is it normal for Iris odaesanensis seed pod stems to curl around?